U.S. patent number 4,767,136 [Application Number 07/063,435] was granted by the patent office on 1988-08-30 for tight coupling device for two rigid, fixed pipes.
This patent grant is currently assigned to Cogema, Compagnie Generale des Matieres Nucleaires. Invention is credited to Jean Lehmann.
United States Patent |
4,767,136 |
Lehmann |
August 30, 1988 |
Tight coupling device for two rigid, fixed pipes
Abstract
The device for coupling two pipes comprises a variable length
assembly formed from two tubular parts, whereof the internal
diameter corresponds to the internal diameter of the pipes. The
tight coupling of this assembly to the ends of the pipes is brought
about by compressing O-rings between a planar surface and a
spherical surface by means of two nuts. The two tubular parts are
then tightly joined by actuating a nut compressing a third
O-ring.
Inventors: |
Lehmann; Jean (Antony,
FR) |
Assignee: |
Cogema, Compagnie Generale des
Matieres Nucleaires (Velizy Villacoublay, FR)
|
Family
ID: |
9336455 |
Appl.
No.: |
07/063,435 |
Filed: |
June 18, 1987 |
Foreign Application Priority Data
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Jun 18, 1986 [FR] |
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86 08803 |
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Current U.S.
Class: |
285/32; 285/39;
285/364; 285/325 |
Current CPC
Class: |
F16L
37/26 (20130101); F16L 25/12 (20130101) |
Current International
Class: |
F16L
37/00 (20060101); F16L 25/12 (20060101); F16L
25/00 (20060101); F16L 37/26 (20060101); F16L
015/02 () |
Field of
Search: |
;285/32,31,39,325,327,364 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0124430 |
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Nov 1984 |
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EP |
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929404 |
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Jun 1955 |
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DE |
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3146305 |
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May 1983 |
|
DE |
|
1253963 |
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Jan 1961 |
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FR |
|
1457568 |
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Sep 1966 |
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FR |
|
1536180 |
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Aug 1968 |
|
FR |
|
873886 |
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Aug 1961 |
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GB |
|
Primary Examiner: Callaghan; Thomas F.
Attorney, Agent or Firm: Kerkam, Stowell, Kondracki &
Clarke
Claims
What is claimed is:
1. A device for the tight coupling of two rigid, fixed pipes,
whereof the axes can suffer from alignment deficiencies, wherein it
comprises two first flanges integral with the ends of said pipes,
each of these flanges having an end surface and a bearing surface
oriented in opposite directions with respect to said end surface;
two coaxial tubular parts, one cylindrical end of a first of these
parts being slidingly received in a threaded end of the second
part, each of these parts having at its opposite end a second
flange having an end surface which can be positioned facing the end
surface of one of the first flanges, one of the end surfaces facing
the first and second flanges being a spherical surface and the
other surface being planar; two first O-rings placed between the
facing end surfaces of the first and second flanges; retaining nuts
for the O-rings screwed onto two threads respectively formed on
said parts, in the vicinity of the second flange, each nut having a
bearing surface able to come into contact with the bearing surface
of the first flange; a tight coupling nut between said parts and
screwed onto the threaded end of the second part; and a third
O-ring, placed around the cylindrical end of the first part,
between two facing conical surfaces respectively formed at the end
of the second part and on the coupling nut, the distance between
said conical surfaces increasing radially inwards.
2. A device according to claim 1, wherein the first part has a
threaded portion adjacent to its cylindrical end, a nut for
unlocking the two parts being screwed onto said threaded portion
and incorporates a member which can bear on an abutment surface
formed on the coupling nut in order to move the latter towards the
opposite end of the first part.
3. A device according to claim 2, wherein a drive sleeve is mounted
so as to rotate freely on the first part and cooperates with the
unlocking nut by rotational means.
4. A device according to claim 1, wherein means are provided for
preventing relative rotation between the two tubular parts.
5. A device according to claim 1, wherein each of the tubular parts
has at least one portion permitting its immobilization in rotation
by an appropriate tool.
6. A device according to claim 1, wherein each of the said parts
has, in the vicinity of the second flange, an inner tubular portion
carrying the latter and an outer tubular portion on which is formed
the said thread, said two tubular portions being interconnected at
a location displaced on moving away from the second flange compared
with the locking nut.
7. A device according to claim 1, wherein the first flanges are
shaped like cradles on which the bearing surface and end surface
face one another.
8. A device according to claim 1, wherein the O-rings are metal
joints.
9. A device according to claim 1, wherein the two first O-rings are
mounted in handling plates.
10. A device according to claim 1, wherein the end surfaces of the
first flanges are planar and the end surfaces of the second flanges
spherical.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a device for bringing about the
tight coupling of two rigid, fixed pipes, particularly when the
axes of said pipes can have alignment deficiencies resulting from
an angular and/or lateral displacement between said axes.
In a large number of industrial installations, fixed equipments are
interconncted by rigid pipes carrying fluids of different types.
When such an installation is installed, it is rarely possible to
reciprocally set up the equipment in such a way that the axes of
the ends of the pipes connecting them are aligned. The problem is
made more complicated as the number of pipes increases.
In addition, certain equipment must be replaced after a certain
period of use. Bearing in mind the manufacturing tolerances of such
equipment, even if two pipes were initially aligned, said alignment
normally no longer exists after such a replacement.
In numerous cases, the sealing of the coupling between the pipes
makes it necessary to use coupling devices taking into account the
alignment deficiencies existing between the pipes.
One known solution for solving this problem consists of using a
flexible compensator, whose ends are fixed to flanges, which are
tightly connected to fixed flanges at the ends of the pipes. For
this purpose, gaskets are generally compressed between adjacent
flanges or clamps, e.g. using tie rods passing through them.
Although this solution makes it possible to solve the problem, of
the tight coupling of two unaligned pipes, it suffers from certain
disadvantages preventing it use in other cases.
Thus, the presence of a flexible compensator between the two pipes
produces at this location a retention zone. When the fluid
transported is corrosive, in a relatively short time said retention
zone may lead to a break in the seal of the compensator, under the
effect of the corrosive action of the fluid stagnating in this
zone. This retention zone can also lead to disturbances in the
circulation of a liquid, such as water hammer, when air or another
gas is trapped in said zone during liquid circulation stoppage.
Situations of this type occur in certain sectors of the chemical
industry and in the nuclear industry.
To illustrate the latter case, reference is made to installations
for the processing of irradiated nuclear fuels, in which the
different equipments are generally located in tight confinement
cells separated by walls traversed by pipes in which circulate
normally corrosive fluids.
In the nuclear industry, the aforementioned problems are made worse
because the coupling of the pipes, particularly during the
replacement of one of the equipments, can only take place remotely
using remote manipulators or similar handling equipment.
The invention relates to a novel device for the tight coupling of
rigid, fixed pipes making it possible to compensate any alignment
defects between said pipes, which does not have the disadvantages
of flexible or bellows compensators referred to hereinbefore and
which can be advantageously installed and removed remotely using
standard handling equipment.
SUMMARY OF THE INVENTION
The present invention therefore relates to a device for the tight
coupling of two rigid, fixed pipes, whereof the axes can suffer
from alignment deficiencies, wherein it comprises two first flanges
integral with the ends of said pipes, each of these flanges having
an end surface and a bearing surface oriented in opposite
directions with respect to said end surface; two coaxial tubular
parts, one cylindrical end of a first of these parts being
slidingly received in a threaded end of the second part, each of
these parts having at its opposite end a second flange having an
end surface which can be positioned facing the end surface of one
of the first flanges, one of the end surfaces facing the first and
second flanges being a spherical surface and the other surface
being planar; two first O-rings placed between the facing end
surfaces of the first and second flanges; retaining nuts for the
O-rings screwed onto two threads respectively formed on said parts,
in the vicinity of the second flange, each nut having a bearing
surface able to come into contact with the bearing surface of the
first flange; a tight coupling nut between said part and screwed
onto the threaded end of the second part; and a third O-ring,
placed around the cylindrical end of the first part, between two
facing conical surfaces respectively formed at the end of the
second part and on the coupling nut, the distance between said
conical surfaces increasing radially inwards.
In such a device, the use of O-rings placed between two flanges
having respectively a spherical surface and a planar surface makes
it possible to ensure the sealing between each of the tubular parts
and the corresponding pipe, no matter what the axial and/or lateral
displacement existing between the axes of the pipes. The seal
between the tubular parts is brought about by the third O-ring,
which is in contact both with the outer surface of one of the
parts, the end of the other part and the coupling nut.
Moreover, the use of two coaxial tubular parts makes it possible to
reduce to a substantially negligible volume the retention zone and
thus eliminate the disadvantages inherent in the flexible
compensators normally used in such a case.
The locking and unlocking of the different parts of the coupling
device are brought about by nuts, whose rotation can easily be
remotely controlled, e.g. by shaping these nuts like capstans.
When the coupling device has to be dismantled after a certain
period of operation, the coupling nut ensuring the locking of the
third O-ring may have siezed up. In such a situation, it would not
be possible to slide the two tubular parts with respect to one
another in order to shorten the coupling device before dismantling
it.
Advantageously, this disadvantage is eliminated by providing on the
first part a threaded portion adjacent to its cylindrical end, an
unlocking nut for said parts being screwed onto said threaded
portion and has a member which can bear on an abutment surface
formed on the coupling nut in order to displace the latter and the
second part towards the said opposite end of the first part.
Preferably, a driving sleeve is then mounted so as to freely rotate
on the first part and cooperate with the unlocking nut by rotary
means.
According to a preferred embodiment of the invention, means are
provided for preventing any relative rotation between the two
tubular parts. In this embodiment, each of the tubular parts has at
least one portion permitting its immobilization in rotation by an
appropriate tool. This further improves the remote handling of the
device.
When the device has been used for a certain period of time, it may
also prove to be impossible to unlock the lock nuts of the joints.
Bearing in mind the special structure of this device, its
dismantling would then be impossible without damaging the ends of
the pipes. To eliminate this disadvantage, each of the parts
advantageously has in the vicinity of the second flange an internal
tubular portion carrying the latter and an external tubular portion
on which is formed the said thread, said two tubular portions being
interconnected at a location further from the second flange than
from the lock nut.
Under conditions like those described herein before, this
configuration makes it possible ensure the dismantling of the
coupling device by the simultaneous cutting of the internal and
external tubular portions of each of the parts. The coupling device
is then freed from the pipes without damaging the latter.
Preferably and to further facilitate the remote handling of the
device, the first flanges are shaped like cradles on which the end
surface and bearing surface face one another.
Advantageously, the O-rings are metal joints, the remote handling
of the end joints being made easier by fitting them in handling
plates.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail hereinafter relative
to non-limitative embodiments and the attached drawings, wherein
show:
FIG. 1, diagrammatically the installation of a tight coupling
device according to the invention between the ends of two pipes
having an alignment deficiency.
FIG. 2, a view comparable to FIG. 1 illustrating the position
occupied by the different elements of the coupling device when the
latter has been positioned between the end of the pipes.
FIG. 3, the same coupling after tightening or locking.
FIG. 4, a longitudinal sectional view on a larger scale of the
central portion of the coupling device of FIGS. 1 to 3.
FIG. 5, a view comparable to FIG. 4 illustrating the obtaining of
the the seal between the two tubular parts of the device.
FIG. 6, a view identical to FIG. 5 illustrating the unlocking of
the two tubular parts in order to shorten the device during its
dismantling.
FIG. 7 a larger scale, longitudinal sectional view illustrating a
constructional variant of the ends of the device according to the
invention making it possible to release said device in the case of
seizing .
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows the ends of two pipes 10a and 10b, which have to be
tightly coupled. As is very diagrammatically shown, compared with
the ideal theoretical positions indicated at a and b, the centers
a.sub.1 and b.sub.1 of the ends of pipes 10a and 10b are spatially
displaced by a certain distance. In the same way, compared with the
common theoretical axis thereof indicated at x, y the real axes
x.sub.1 and y.sub.1 of each of the pipes 10a, 10b are angularly
displaced. In practice, the distance separating points a.sub.1 and
b.sub.1 from theoretical point a and b can be 6 mm and the angular
displacement between each of the axes x.sub.1 and y.sub.1 and the
theoretical axis x.sub.y can reach 1.degree..
According to the invention, the tight coupling between pipes 10a,
10b having such displacements is brought about by means of a
coupling device designated by the general reference 12. Device 12
firstly comprises, at the end of each of the pipes 10a, 10b, a
cradle-shaped flange 14a and 14b. Only flange 14a will be described
in greater detail. Flange 14b is identical to flange 14a and its
components are designated by the same references, followed by b
instead of a.
Cradle-shaped flange 14a comprises a portion 15a forming the actual
flange fixed to the end of pipe 10a. Said portion 15a forming the
flange has an end surface 16a through which issues pipe 10a. Flange
14a is extended beyond surface 16a by a cradle-shaped portion 17a
and has in section the shape of a U open towards the top. At its
end, portion 17a is extended by a plate 19a having a planar bearing
surface 18a parallel to surface 16a and facing the latter. In the
extension of pipe 10a, plate 19a also has a notch 20a which is open
in the upwards direction.
Coupling device 12 according to the invention also comprises a
variable length, detachable tubular assembly 21 mainly constituted
by two coaxial tubular parts 22a, 22b.
As can best be seen from FIGS. 2 and 4, one cylindrical end 23a of
part 22a slidingly penetrates one larger diameter end 23b of the
bore formed in part 22b. Ouside said end 23b, bores 25a and 25b
formed in parts 22a and 22b have a uniform diameter equal to the
internal diameter of the pipes 10a, 10b to be connected. Thus,
substantially no retention zone is created.
In the represented embodiment, parts 22a, 22b have their reciprocal
displacement limited by means of a lug 24 fixed to tubular part 22b
and projecting radially inwards into the larger diameter end 23b of
bore 25b. Lug 24 penetrates a longitudinal slot 26 formed in the
cylindrical end 23a of tubular part 22a.
At its end in which is received the tubular end 23a of part 22a,
part 22b has on its outer surface a thread 28, on which is screwed
a coupling nut 30. This nut 30 is castellated on a portion 32 of
its outer surface, so as to form a capstan, whereof the rotation
can be remotely controlled, e.g. with a tool 33 shown in FIG. 1.
This tool comprises a rotary mandrel 35, whose axis is
perpendicular to that of assembly 21 and which has fingers meshing
in the castellated portion 32 of nut 30, in order to control the
rotation thereof.
Nut 30 is extended beyond the end of part 22b in order to form a
tubular portion 34, whose inner surface has end bearing surfaces
which cooperate without clearance with the cylindrical outer
surface of end 23a of a part 22a. This cooperation ensures a
perfect alignment of the axes of parts 22a and 22b.
The planar end face of tubular portion 34 turned towards the end of
part 22b serves as a bearing support for a trapezoidal section
annular part 36 via a roller bearing 38. End face 40 of part 22b,
as well as face 42 of part 36 facing said end face have truncated
cone shapes, such that the distance separating the two faces
increases radially inwards.
An O-ring 44 is placed between surfaces 40, 42, so as to be
simultaneously in contact with these two surfaces and with the
outer cylindrical surface of end 23a of tubular part 22a.
Preferably, O-ring or joint 44 is an elastic metal joint, such as
the Helicoflex joint marketed by Cefilac.
In the arrangement described hereinbefore, the locking of nut 30
has the effect of compressing O-ring 44 between surfaces 40 and 42.
By reaction, bearing in mind the conical shape of the surfaces,
O-ring 44 is also applied to the outer surface of cylindrical end
23a of part 22a. Following the locking of nut 30, tubular parts
22a, 22b are consequently tightly connected.
On referring to FIG. 1, it can seen that at their opposite ends,
tubular parts 22a, 22b are terminated by flanges 46a, 46b.
According to an essential feature of the invention, end surface
48a, 48b of flanges 46a, 46b are spherical surface and preferably
convex.
In the vicinity of flanges 46a, 46b, parts 22a, 22b comprise
thicker portions provided with threads 50a, 50b on their outer
surfaces. Lock nuts 52a and 52b are screwed onto these threads 50a,
50b. Like coupling nut 30, nuts 52a and 52b are castellated on a
portion 54a, 54b of their outer surface. Thus, nuts 52a, 52b form
capstans which can be remotely manipulated, e.g. with the aid of
tool 33.
Beyond said castellated portion 54a, 54b, each of the nuts 52a, 52b
is extended towards flange 46a, 46b and is terminated by a
flange-like part 56a, 56b. The face of the part 56a, 56b opposite
to flange 46a, 46b is spherical, preferably convex and serves as a
bearing support for a complementary washer 58a, 58b. The latter has
a planar bearing face 60a, 60b oriented in the opposite direction
compared with the spherical end surface 48a, 48b of the
corresponding flange.
As illustrated in FIG. 2, when assembly 21 is placed between the
ends of pipes 10a, 10b, the spherical end surfaces 48a, 48b are
positioned facing the planar end surfaces 16a, 16b. Bearing
surfaces 60a, 60b then face bearing surfaces 18a, 18b.
The tight coupling device 12 according to the invention also
comprises two O-rings 62a, 62b positioned between end surfaces 16a
and 48a and 16b and 48b respectively. Like O-ring 44, O-rings 62a,
62b are preferably flexible metallic joints, such as Helicoflex
joints, marketed by Cefilac.
In order to permit the remote handling thereof, O-ring 62a, 62b are
mounted on metal plates 64a, 64b shown diagrammatically in FIG.
1.
Before assembly 21 is placed between the ends of pipes 10a, 10b,
its length is adjusted by unlocking nut 30 forming a capstan and
nuts 52a, 52b in the form of a capstan are actuated in order to
move bearing surfaces 60a, 60b towards end surfaces 48a, 48b. This
configuration is illustrated in FIG. 2, where it is possible to see
that O-rings 62a and 62b are then in place.
As illustrated in FIG. 3 (arrows F.sub.1a and F.sub.1b), nuts 52a,
52b are then actuated in turn, in order to compress the O-rings
62a, 62b between the end faces of the adjacent flanges.
For O-ring 62a, this result is obtained by making face 60a bear
against face 18a and then by continuing to screw nut 52a onto
thread 50a. By reaction, the tubular part 22a is then displaced to
the left with respect to FIG. 3, which has the effect of
compressing O-ring 62a between end surfaces 48a and 16a.
A similar operation is then carried out at the other end of
assembly 21, in order to tightly connect tubular part 22b to pipe
10b.
According to the invention, the cooperation of O-rings 62a, 62b
with the spherical end surfaces 48a, 48b of flanges 46a, 46b makes
it possible to ensure the tight coupling of tubular parts 22a, 22b
on pipes 10a, 10b, despite the displacements generally existing
between the theoretical and real positions of the ends of these
pipes and the possible angular displacement of their axes.
When the ends of assembly 21 are tightly connected to the ends of
pipes 10a, 10b in the manner described hereinbefore, it is merely
necessary to ensure the tight connection of tubular parts 22a,
22b.
According to the invention and as illustrated in FIGS. 3 and 5,
this result is obtained by actuating nut 30, in order to move it to
the right. Thus, O-ring 44 is compressed between surfaces 42 and 40
and, bearing in mind the truncated cone shape of the latter,
against the outer cylindrical surface of end 23a of part 22a. Thus,
sealing between parts 22a, 22b is ensured.
As is also illustrated by FIGS. 1 to 3, in order to prevent the
rotation of tubular parts 22a, 22b during the rotation of nuts 30,
52a and 52b, each of these tubular parts preferably has portions
66a, 66b, permitting the immobilization in rotation thereof with an
appropriate tool, such as the spanner 37 diagrammatically shown in
FIG. 1. Portion 66a, 66b can in particular have a square or
hexagonal section.
When it is wished to dismantle the coupling device 12 according to
the invention, e.g. to change one of the equipments which it
connects, it is normally sufficient to carry out identical
operations to those performed during its fitting, but in the
reverse order. Thus, the tight coupling between the two tubular
parts 22a, 22b is normally released by actuating nut 30, after
which the ends of the device can in turn be disengaged from the
ends of the pipes by the actuation of nuts 52a, 52b.
However, when the device has been in service for several years and
particularly if it has been working in a particularly corrosive
medium, nut 30 frequently becomes seized on the tubular parts. In
this case, it is not possible to disengage tubular parts 22a, 22b
by actuating the nut.
In order to obviate this disadvantage, in the preferred embodiment
of the invention shown in FIG. 1 to 6, an unlocking nut 68 is
screwed onto a thread 70 (FIG. 4) formed on the outer surface of a
part 72, joined by welding to the tubular end 23a of part 22a.
More specifically part 72 is welded to part 22a beyond the end of
portion 34 of nut 30 and thread 70 is formed on a tubular portion
of the part 72 surrounding portion 34.
The displacement of nut 68 parallel to the common axis of the parts
22a, 22b with respect to nut 30 is limited in one or other
direction by a screw 74 screwed radially into part 68 and whose end
penetrate a groove 76 formed on the outer surface of nut 30 between
the castellated portion 32 and the tubular portion 34.
In the embodiment shown in FIG. 4, the rotation of nut 68 is
controlled by a sleeve 78 arranged around nut 68. Sleeve 78 is
integral in rotation with nut 60 as a result of complementary
splines 80.
Moreover, sleeve 80 is axially immobilized on part 72 as a result
of a two-piece washer 82 fixed to the end of sleeve 78 turned
towards nut 52a, e.g. by means of screw 84. The inner peripheral
edge of washer 82 penetrates a complementary groove 86 formed on
the outer surface of part 72.
The relative displacement between nut 68 and sleeve 78 parallel to
the common axis of parts 22a, 22b is limited by a screw 88 fixed
radially in nut 68 and traversing an oblong hole 90 formed in a
tubular part 92 joined to sleeve 78, e.g. my means of screw 94.
In order to ensure its rotation, sleeve 78 has a castellated
external portion 96 giving it the shape of a capstan, which can be
remotely actuated by means of a tool, like 33 in FIG. 1.
As a result of the features described hereinbefore and as is
particularly illustrated in FIG. 6, if nut 30 becomes seized, it is
still possible to slide the two tubular parts 22a and 22b with
respect to one another in the sense of shortening the same.
Thus, by rotating sleeve 78 and consequently nut 68 in the
direction of arrow F.sub.3 in FIG. 6, the end of screw 74 is made
to bear on the left-hand edge of groove 76 when considering this
drawing. On continuing this movement, there is a leftward
displacement of nut 30 and consequently tubular part 22b on which
it is screwed with respect to the tubular part 22a on which the
sleeve 78 is axially mobilized. The corresponding displacement,
represented diagrammatically by arrow F.sub.4 in FIG. 6, makes it
possible to bring about the desired shortening, even in the case of
nut 30 seizing.
Under the same conditions of prolonged use of the coupling device
according to the invention, there can also be seizing of nuts 52a,
52b permitting the coupling of the device to the ends of the pipes.
To obviate this disadvantage, FIG. 7 shows a variant of the
coupling device according to the invention. This differs
essentially from the previously described embodiment by the fact
that in place of being directly formed on a widened portion of part
22a, 22b carrying flange 46a, 46b, thread 50a, 50b is formed on a
separate portion.
This structure will now be described in greater detail with
reference to FIG. 7, for the end of tubular part 22a. Obviously, an
identical structure appears at the end of tubular part 22b.
At the vicinity of its end carrying flange 46a, tubular part 22a
comprises an inner tubular portion 102a carrying flange 46a and an
outer tubular portion 100a positioned coaxially around portion 102.
These two tubular portions 100a 102a are interconnected, e.g. by
being welded to a thicker portion 104a, which is axially displaced
on moving away from flange 46a with respect to thread 50a and nut
52a.
Thus, between portion 104a and nut 52a, a zone is formed in which
it is possible to simultaneously cut the two tubular portions 100a
and 102a, as indicated by arrow F.sub.5 in FIG. 7. By carrying out
such cutting, it is possible to disengage the ends of the device
according to the invention from the ends of the pipes. Thus, it is
possible to dismantle the device without damaging the pipes.
Obviously, the invention is not limited to the embodiments
described and in fact covers all variants thereof. In particular,
when the fitting and dismantling of the device according to the
invention take place relatively frequently, so that there is no
risk of seizing, nut 68 and sleeve 78 can be eliminated and the
variant described relative to FIG. 7 is unnecessary.
* * * * *